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Naturwissenschaften

, Volume 99, Issue 2, pp 133–141 | Cite as

Diversity in the later Paleogene proboscidean radiation: a small barytheriid from the Oligocene of Dhofar Governorate, Sultanate of Oman

  • Erik R. Seiffert
  • Sobhi Nasir
  • Abdulrahman Al-Harthy
  • Joseph R. Groenke
  • Brian P. Kraatz
  • Nancy J. Stevens
  • Abdul Razak Al-Sayigh
Original Paper

Abstract

Despite significant recent improvements to our understanding of the early evolution of the Order Proboscidea (elephants and their extinct relatives), geographic sampling of the group’s Paleogene fossil record remains strongly biased, with the first ~30 million years of proboscidean evolution documented solely in near-coastal deposits of northern Africa. The considerable morphological disparity that is observable among the late Eocene and early Oligocene proboscideans of northern Africa suggests that other, as yet unsampled, parts of Afro-Arabia might have served as important centers for the early diversification of major proboscidean clades. Here we describe the oldest taxonomically diagnostic remains of a fossil proboscidean from the Arabian Peninsula, a partial mandible of Omanitherium dhofarensis (new genus and species), from near the base of the early Oligocene Shizar Member of the Ashawq Formation, in the Dhofar Governorate of the Sultanate of Oman. The molars and premolars of Omanitherium are morphologically intermediate between those of Arcanotherium and Barytherium from northern Africa, but its specialized lower incisors are unlike those of other known Paleogene proboscideans in being greatly enlarged, high-crowned, conical, and tusk-like. Omanitherium is consistently placed close to late Eocene Barytherium in our phylogenetic analyses, and we place the new genus in the Family Barytheriidae. Some features of Omanitherium, such as tusk-like lower second incisors, the possible loss of the lower central incisors, an enlarged anterior mental foramen, and inferred elongate mandibular symphysis and diminutive P2, suggest a possible phylogenetic link with Deinotheriidae, an extinct family of proboscideans whose origins have long been mysterious.

Keywords

Afro-Arabia Afrotheria Paenungulata Tethytheria Deinotheriidae 

Notes

Acknowledgments

We gratefully acknowledge Mr. Ahmed Al-Awaid for discovering and collecting part of the Omanitherium dhofarensis holotype, reporting it to the Office of Adviser to His Majesty the Sultan for Cultural Affairs, and guiding E.R.S., S.N., and A.A.-H. back to the locality in 2010. Fieldwork in the Dhofar area was funded by Sultan Qaboos University. Funding for E.R.S.’ research on Paleogene proboscideans and their living and extinct relatives was provided by the U.S. National Science Foundation and The Leakey Foundation, and access to fossil material and casts has been provided by Y. Attia, P. Chatrath, E. Gheerbrant, J. Hooker, and R. Tabuce. H. Al-Zidi and A. Al-Farsi provided technical assistance during fossil preparation. R. Asher, B. Beatty, W. Sanders, and an anonymous reviewer provided valuable comments that improved the manuscript. M. Steiper provided access to computer facilities for the phylogenetic analyses and photos of fossil proboscideans.

Supplementary material

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ESM 1 (PDF 1482 kb)

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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Erik R. Seiffert
    • 1
  • Sobhi Nasir
    • 2
  • Abdulrahman Al-Harthy
    • 2
  • Joseph R. Groenke
    • 1
  • Brian P. Kraatz
    • 3
  • Nancy J. Stevens
    • 4
  • Abdul Razak Al-Sayigh
    • 2
  1. 1.Department of Anatomical Sciences, Health Sciences Center T-8Stony Brook UniversityStony BrookUSA
  2. 2.Department of Earth Sciences, College of ScienceSultan Qaboos UniversityMuscatSultanate of Oman
  3. 3.Department of AnatomyWestern University of Health SciencesPomonaUSA
  4. 4.Department of Biomedical Sciences, Heritage College of Osteopathic MedicineOhio UniversityAthensUSA

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